Dynamic Neuromuscular Control Research Articles

Hybrid Percutaneous Management of Acute Midsubstance Achilles Tendon Ruptures

Background: Operative management techniques of Achilles tendon ruptures can be categorized into open repair, mini-open repair, or percutaneous repair. Indications: Surgical repair of acute ruptures of the Achilles tendon is indicated in athletic populations, with percutaneous repair being an effective technique with more favorable outcomes. Technique: With the patient prone, the Achilles rupture is identified and the Percutaneous Achilles Repair System (PARS) jig is inserted under the proximal paratenon. A series of Keith needles and flat braided SutureTape sutures are passed transversely across the proximal stump of the tendon. The sutures are then shuttled through the distal stump using a SutureLasso through medial and lateral percutaneous incisions on the distal medial and distal lateral borders of Achilles, respectively. Sutures are passed, tensioned, and secured to the posterior tuberosity of the calcaneus with two SwiveLock anchors. Results: Percutaneous repair, compared with open repair, results in lower wound complication rates, improved cosmetic appearance and fewer adhesions. Following surgery, patients follow a 5-stage rehabilitation protocol with return to sport when patients demonstrate dynamic neuromuscular control during multiplane activities without pain or swelling. Outcome studies have compared percutaneous repairs to open repairs, with percutaneous repairs demonstrating a quicker return to work or baseline activities (2.8 months versus 5.6 months) and a shorter return to play for athletes (average 18 weeks). Also, a greater number of PARS patients were able to return to baseline activities within 5 months (98%), compared with open repair patients (82%; P = .0001). In a prospective randomized controlled trial of 33 patients, Lim et al reported no postoperative wound infections in the percutaneous group and a 21% infection rate in the open repair group ( P = .01). Finally, in a recent systematic review of only percutaneous repairs, reported rates of sural nerve injury and rerupture were only 3.3% and 2.1%, respectively. Discussion/Conclusion: Compared to open repair, percutaneous Achilles repair allows for decreased risk of soft-tissue complications with comparable functional outcomes and earlier return to activity. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Co-creation of an exercise inventory to improve scapular stabilization and control among individuals with rotator cuff-related shoulder pain: a survey-based study amongst physiotherapists

BackgroundScapular stabilization exercises (SSE) are often included in the treatment of individuals with rotator cuff-related shoulder pain (RCRSP) to decrease pain and improve function. These SSE typically aim to strengthen the scapular muscles and optimize dynamic neuromuscular control of the scapula, which may improve overall shoulder stability and movement quality. No consensus of the recommended SSE for the management of RCRSP is available. Hence, this study aimed to consult physiotherapists to co-create an inventory of recommended SSE based on the exercise’s relevance and frequency of prescriptions for the rehabilitation of individuals with RCRSP.MethodsA group of 16 physiotherapists with experience in treating shoulder pain participated in a sequential consultation incorporating two distinct rounds of consultation focusing on SSE (modified Delphi design). In round 1, physiotherapists identified and demonstrated up to 10 SSE that they commonly recommend or use among individuals with RCRSP. The description and performance of all SSE were audio and video recorded. All SSE suggested by more than one participant in round 1 advanced to round 2. In round 2, physiotherapists rated these SSE on a 4-point Likert scale according to their perceived relevance and frequency of prescription for this population.ResultsIn round 1, out of the 25 SSE recommended by participants, 19 SSE (76.0%) were recommended by more than one physiotherapist and advanced to round 2. In round 2, 13 SSE were consensually classified (agreement ≥75%) as being relevant for the rehabilitation of individuals with RCRSP. SSE targeting the recruitment of the serratus anterior and lower trapezius muscles were considered the most relevant for the management of RCRSP, whereas SSE targeting neuromuscular scapular control were the most prescribed SSE for the management of RCRSP.ConclusionsAn inventory composed of 13 SSE was co-created by physiotherapists based on their relevance and frequency of prescription for the rehabilitation of individuals with RCRSP. When designing an exercise program, physiotherapists can use this SSE inventory to inform their exercise selection, in combination with their current knowledge on shoulder rehabilitation, as well as patients’ preferences.

Systematic Review and Meta-Analysis of the Y-Balance Test Lower Quarter: Reliability, Discriminant Validity, and Predictive Validity.

BackgroundDeficits in dynamic neuromuscular control have been associated with post-injury sequelae and increased injury risk. The Y-Balance Test Lower Quarter (YBT-LQ) has emerged as a tool to identify these deficits.PurposeTo review the reliability of the YBT-LQ, determine if performance on the YBT-LQ varies among populations (i.e., sex, sport/activity, and competition level), and to determine the injury risk identification validity of the YBT-LQ based on asymmetry, individual reach direction performance, or composite score.Study DesignSystematic ReviewMethodsA comprehensive search was performed of 10 online databases from inception to October 30, 2019. Only studies that tested dynamic single leg balance using the YBT-LQ were included. Studies were excluded if the Y-Balance Test kit was not utilized during testing or if there was a major deviation from the Y-Balance test procedure. For methodological quality assessment, the modified Downs and Black scale and the Newcastle-Ottawa Scale were used.ResultsFifty-seven studies (four in multiple categories) were included with nine studies assessing reliability, 36 assessing population differences, and 16 assessing injury prediction were included. Intra-rater reliability ranged from 0.85-0.91. Sex differences were observed in the posteromedial direction (males: 109.6 [95%CI 107.4-111.8]; females: 102.3 [95%CI 97.2-107.4; p = 0.01]) and posterolateral direction (males: 107.0 [95%CI 105.0-109.1]; females: 102.0 [95%CI 97.8-106.2]). However, no difference was observed between sexes in the anterior reach direction (males: 71.9 [95%CI 69.5-74.5]; females: 70.8 [95%CI 65.7-75.9]; p=0.708). Differences in composite score were noted between soccer (97.6; 95%CI 95.9-99.3) and basketball (92.8; 95%CI 90.4-95.3; p <0.01), and baseball (97.4; 95%CI 94.6-100.2) and basketball (92.8; 95%CI 90.4-95.3; p=0.02). Given the heterogeneity of injury prediction studies, a meta-analysis of these data was not possible. Three of the 13 studies reported a relationship between anterior reach asymmetry reach and injury risk, three of 10 studies for posteromedial and posterolateral reach asymmetry, and one of 13 studies reported relationship with composite reach asymmetry.ConclusionsThere was moderate to high quality evidence demonstrating that the YBT-LQ is a reliable dynamic neuromuscular control test. Significant differences in sex and sport were observed. If general cut points (i.e., not population specific) are used, the YBT-LQ may not be predictive of injury. Clinical population specific requirements (e.g., age, sex, sport/activity) should be considered when interpreting YBT-LQ performance, particularly when used to identify risk factors for injury.Level of Evidence1b

A comparison of coordination and its variability in lower extremity segments during treadmill and overground running at different speeds

BackgroundRecently, the use of treadmills for walking and running has increased due to lifestyle changes. However, biomechanical differences in coordination between running on a treadmill or overground have not been adequately addressed. Research questionThe purpose of this study was to compare coordination and its variability in lower limb segments during treadmill and overground running at different speeds. MethodsTwenty physically active university undergraduate students participated in this study. Each participant ran trials for both overground and treadmill running at slow and fast speeds. Three-dimensional kinematic data of the lower limb segments were captured. The continuous relative phase (CRP) was used to compute coordination and its variability (VCRP) for foot, shank, and thigh segments of the dominant side of the participants. ResultsA vector analysis using statistical parametric mapping (SPM) revealed that there were statistically significant differences in the calculated CRPs for treadmill and overground running in the stance phase of running and for different running speeds in the late stance and swing phases. However, the VCRPs calculated for the two locations and speeds did not exhibit any statistically significant differences. ConclusionThe findings of this study suggest differences in segment coupling between treadmill and overground running may affect lower extremity biomechanics. In addition, changes in the coupling patterns for different running speeds suggest that segment coordination is not stable in the range of training speeds used by runners. Finally, the lack of differences in the variability of segment couplings during treadmill and overground conditions at different speeds potentially demonstrates similar dynamic neuromuscular control and degrees of freedom at these different running locations and speeds.

A neuromuscular training program enhances dynamic neuromuscular control and physical performance in court‐sport athletes

This study aimed to investigate the effects of an 8-week neuromuscular training pro-tocol on dynamic neuromuscular control and physical performance. Twenty female court-sport athletes were randomly allocated to two groups, a control (n = 10) and an intervention group (n = 10). All participants performed pre-testing inclusive of a 20-m sprint, countermovement jump (CMJ), Illinois agility test, and the qualita-tive analysis of a single-leg squat (QASLS), which is an assessment of dynamic neuromuscular control. Subsequently the intervention group engaged in a modified version of the FIFA 11+ neuromuscular training program twice weekly for 8 weeks. At post-testing, there were between-group differences in CMJ (intervention; +3.96-cm vs control; −1.36-cm, P = .003) and QASLS for both legs (P < .001) (right leg, intervention; pre: 3.75, post: 1.91, and control; pre: 4.11, post: 4.08) (left leg, inter-vention; pre: 3.72, post: 0.98, and control; pre: 4.05, post: 4.23). There was a within-group improvement in 20-m sprint for the intervention group only post-training (pre: 3.69-seconds; post: 3.60-seconds, P = .043), while no differences occurred in Illinois agility test for either group. A modified FIFA 11+ protocol can be considered an ef-fective neuromuscular training program for enhancing dynamic neuromuscular con-trol and sport-specific physical performance in female court-sport athletes.

EFFICACY OF PERTURBATION-ENHANCED NEUROMUSCULAR TRAINING ON HAMSTRING AND QUADRICEPS ONSET TIME, ACTIVATION AND KNEE FLEXION DURING A TUCK-JUMP TASK

Deficits in dynamic neuromuscular control of the knee may contribute to the higher incidence of the anterior cruciate ligament (ACL), specifically in female athletes. Little is known about the effects of preventive training programs on muscle onset time and activation during functional tasks. The purpose of this study was to evaluate the efficacy of perturbation-enhanced neuromuscular training on hamstring and quadriceps onset time and activation, and knee flexion angle in female athletes with quadriceps dominance (QD) deficit during a tuck-jump (TJ) task. Quasi-experimental study. Thirty-one collegiate female athletes with neuromuscular quadriceps dominance deficit randomly divided into experimental (n=16) and control (n=15) group. The experimental group performed a six-week perturbation training (18 sessions). Electromyograhic (EMG) assessment of quadriceps and hamstring activation and knee flexion angles during a TJ task were completed at baseline and after six weeks. A significant decrease in the preparatory(p=0.003) and reactive (p=0.013) quadriceps-hamstring (Q/H) co-activation ratio was found in the experimental group. Perturbation training markedly decreased latency in medial hamstring (MH) (p=0.001), vastus medialis (VM) (p=0.004) and lateral hamstring (LH) (p=0.031), while latency increased for rectus femoris (RF) (p=0.001) and vastus lateralis (VL) (p=0.023) during a TJ task. The experimental group had average increases of 41.1%, 40.8%, and 39.5% in initial knee flexion, peak knee flexion and knee flexion displacement angle during the TJ task, respectively. Increased preparatory VM and MH activities and decreased Q/H co-activation ratio, decreased VM and MH latency represent preprogrammed motor strategies learned during the perturbation training. This observed neuromuscular adaptation during TJ task could potentially reduce the risk for non-contact ACL injury. 2.

Kinematic effects of repeated turns while running

In team sports, non-contact ACL and MCL injuries occur during abrupt changes of direction, like turns or cutting manoeuvres. Fatigue affects dynamic neuromuscular control and increases knee injury risk. This study analysed how lower limb joints and centre-of-mass kinematics are affected throughout a high-intensity running protocol involving repeated 180°-turns. Twenty young men (18–23 years, BMI: 20.8–24.4 kg m−2) completed a 5-m shuttle running trial lasting 5 min at an average speed of 75% of their maximum aerobic speed. During the test, cardio-metabolic parameters were obtained, together with joints and centre-of-mass kinematics, using a motion capture system. Kinematic data were compared between the first and the last minute of exercise. Perceived exercise intensity ranged from “hard” to “maximum exertion” and post-exercise lactate concentration ranged from 5.4 to 15.5 mM. The repetition of 180°-turns induced a substantial reduction of hip (−60%, p < .001, large effect) and knee flexion (−40%, p = .003, medium-to-large effect), and an increase of hip adduction and internal rotation (+25–30%, p < .05, medium-to-large effect). Since such movements are factors increasing the likelihood of non-contact knee injuries, we concluded that the prolonged repetition of turns may expose participants to increased risk of ligament failure. Prevention programmes should include discipline-specific neuromuscular training especially in late practices.

Injury Prevention Strategies for Adolescent Cricket Pace Bowlers

Adolescent cricket pace bowlers are prone to non-contact shoulder, low back and lower-limb injuries. Exercise-based injury prevention programmes (IPPs) are effective for reducing non-contact injuries in athletes; however, a specific programme for adolescent pace bowlers has not been published. This paper therefore seeks to provide a rationale for the development of an exercise-based IPP specific for adolescent pace bowlers. It also outlines design principles and provides an example exercise programme that can be implemented at the community level. In addition, the paper addresses other injury prevention techniques concerned with the prescription of appropriate bowling loads and the modification of poor bowling biomechanics. Performing an exercise-based IPP before cricket training could reduce injury rates in adolescent pace bowlers. Eccentric strengthening exercises can be employed to target injuries to the posterior shoulder muscles, hip adductors and hamstring muscles. The risk of low back, knee and ankle injury could also be reduced with the inclusion of dynamic neuromuscular control exercises and trunk extensor endurance exercises. Other prevention strategies that need to be considered include the modification of poor bowling biomechanics, such as shoulder counter-rotation and lateral trunk flexion. Coaches and players should also aim to quantify bowling load accurately and coaches should use this information to prescribe appropriate individualised bowling loads. Specifically, players would benefit from avoiding both long periods of low load and acute periods when load is excessively high. Future evidence is needed to determine the effectiveness of the example programme outlined in this paper. It would also be beneficial to investigate whether the modification of bowling biomechanics is achievable at the non-elite level and if bowling load can be accurately measured and manipulated within a community-level population.

Effects of proprioceptive training on the incidence of ankle sprain in athletes: systematic review and meta-analysis

Objective: To investigate how dynamic neuromuscular control, postural sway, joint position sense, and incidence of ankle sprain are influenced by balance training in athletes compared with the control group in randomized clinical trials. Data sources: The search strategy included MEDLINE, Physical Therapy Evidence Database, Cochrane Central Register of Controlled Trials, and Latin American and Caribbean Center on Health Sciences Information. Randomized controlled trials (RCTs) were published by June of 2018. Methods: RCTs that evaluate the effectiveness of proprioception in these outcomes: dynamic neuromuscular control, postural sway, joint position, and the incidence of ankle sprains in athletes aged between 18 and 35 years. Two reviewers independently screened the searched records, extracted the data, and assessed risk of bias. The treatment effect sizes were pooled in a meta-analysis using the RevMan 5.2 software. Internal validity was assessed through topics suggested by Cochrane Collaborations. Results: Of the 12 articles included (n = 1817), eight were in the meta-analysis (n = 1722). The balance training reduced the incidence of ankle sprains in 38% compared with the control group (RR: 0.62; 95% CI: 0.43–0.90). In relation to the dynamic neuromuscular control, the training showed increase in the distance of reach in the anterior (0.62 cm, 95% CI: 0.13–1.11), posterolateral (4.22 cm, 95% CI: 1.76–6.68), and posteromedial (3.65 cm, 95% CI: 1.03–6.26) through the Star Excursion Balance test. Furthermore, training seems to improve postural sway and joint position sense. Conclusion: Balance training reduces the incidence of ankle sprains and increases dynamic neuromuscular control, postural sway, and the joint position sense in athletes.

Comparison of neuromuscular and proprioceptive variables between legs during lunge in fencers

The fencer performs the lunge, an attack characterized by a forward push. The objective of the study was to compare the neuromuscular and proprioceptive variables between the front and back legs during the lunge. It was a cross-sectional study of 19 fencers. Measurement of the concentric muscle torque peak of the ankle muscles, as well as muscle balance, through the conventional ratio and functional ratio, was performed through the isokinetic dynamometer. The reaction time (RT) of the peroneus longus (PL), anterior tibial (AT) and lateral gastrocnemius (LG) of both legs was collected from an electromyography during Lunge execution. Dynamic neuromuscular control of the ankles was evaluated by the Star Excursion Balance Test (SEBT) in eight different directions. It was possible to identify a significant difference in the muscular torque of these muscle groups (p ≤ 0.05), as well as in the Conventional Ratio (p = 0.002) and Functional Ratio (p = 0.003) of dorsiflexors/plantiflexors of the back leg in relation to the front, that is, a decrease in the force of back leg. There was also no difference in the RT of the PL and AT (p ≥ 0.05), but have difference in RT of LG during the Lunge (p ≤ 0.05). Furthermore, there is difference in the eight directions of the SEBT (p ≤ 0.05) comparing the back with the front leg. The training performed by fencing athletes is not able to produce similar stimuli for both legs with regard to dynamic neuromuscular control, reaction time and concentric torque of the ankle musculature.

Sex differences in frontal and transverse plane hip and knee kinematics during the modified Star Excursion Balance Test

PurposeThe modified Star Excursion Balance Test (mSEBT) assesses dynamic neuromuscular control, with predictive ability regarding lower extremity injury risk. Previous kinematic mSEBT analyses are limited to sex differences between injured or fatigued populations or non-fatigued groups in the sagittal plane only. We hypothesize that sex differences exist in the frontal and transverse plane kinematics of the hip and knee in healthy, non-fatigued subjects during the mSEBT.MethodsThe descriptive laboratory study involved 38 healthy subjects: 20 males (aged 24.8 ± 2.7 years) and 18 females (24.1 ± 3.7 years). Peak kinematics, obtained by a VICONTM motion system, of the hip and knee in the sagittal, frontal, and transverse plane were compared during the anterior, posteromedial, and posterolateral reach of the mSEBT. Wilcoxon rank test with significant differences at &lt;i&gt;p&lt;/i&gt; &lt; 0.05 was used.ResultsKinematic differences existed between the groups in the frontal and transverse plane of the hip and knee in all reach directions (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). No differences were found in the sagittal plane of the hip or knee between the groups.ConclusionsSex differences exist in frontal and transverse plane kinematics of the hip and knee during the mSEBT. The mSEBT may be enhanced as an injury prediction tool, if frontal and transverse plane kinematics were included during risk assessment screening.

Current Concepts in the Assessment and Rehabilitation of the Thrower’s Shoulder

At the elite level, pitching has been reported as one of the fastest human movements, occurring at angular speeds of 7250°/s. The repetitive nature of overhead throwing can lead to numerous adaptations in the glenohumeral, scapulothoracic, and hip joints. Owing to these unique changes, a comprehensive and sequential rehabilitation program is dependent on a thorough clinical examination. The rehabilitation program should consist of an individualized plan of care that focuses on shoulder mobility, scapular posture and strength, dynamic stability and neuromuscular control of the shoulder complex, as well as core and lower extremity strength. In this article, the adaptations that commonly occur to the thrower׳s shoulder are described and strategies to address them are discussed. A sequential, multiphased rehabilitation program that addresses restoration of motion, strength, endurance, and power is outlined. It is essential to consider the kinetic chain and involvement of the core and lower extremities with throwing and that these regions should not be ignored in the evaluation and treatment of the thrower׳s shoulder. A 4-phase approach, with specific criteria that direct progression to the next phase, is discussed.

Great Britain's Olympians with generalised joint hypermobility have a higher prevalence of knee osteoarthritis

Purpose: Individuals with generalized joint hypermobility (GJH) are reported, in the clinical setting, to be at greater risk of developing musculoskeletal related joint pain, joint dislocations and tendinopathies. It is hypothesized that impaired static and dynamic neuromuscular movement control in those with GJH is responsible for contributing to an increased risk of injury and subsequent knee osteoarthritis (OA). Yet, to date, it remains unproven if there is an association between GJH and knee OA.

The effect of kinesiotape on dynamic balance following muscle fatigue in individuals with chronic ankle instability

This study aimed to evaluate the effect of kinesiotape (KT) on dynamic stability following ankle muscle fatigue among individuals with chronic ankle instability (CAI). Twenty participants with CAI participated in the study. Participants were tested under three conditions: KT, non-elastic tape, and no tape pre- and post-fatigue of the ankle muscles. Ankle muscles fatigue was induced using an isokinetic apparatus, activity of the fibularis muscle was recorded using one-channel vibromyography (VMG), and dynamic balance and neuromuscular control were assessed using the Y-Balance Test. Following fatigue exercises, the VMG signal significantly decreased in all groups (p < 0.01), without differences between groups. No significant difference in dynamic balance test scores was found between the pre- and post-fatigue condition for each group and between groups. Our results demonstrate that KT had no significant effects on dynamic balance and muscle activity following ankle muscle fatigue among individuals with CAI.

Dynamic Neuromuscular Control of the Lower Limbs in Response to Unexpected Single-Planar versus Multi-Planar Support Perturbations in Young, Active Adults.

PurposeAn anterior cruciate ligament (ACL) injury involves a multi-planar injury mechanism. Nevertheless, unexpected multi-planar perturbations have not been used to screen athletes in the context of ACL injury prevention yet could reveal those more at risk. The objective of this study was to compare neuromuscular responses to multi-planar (MPP) and single-planar perturbations (SPP) during a stepping-down task. These results might serve as a basis for future implementation of external perturbations in ACL injury screening programs.MethodsThirteen young adults performed a single leg stepping-down task in eight conditions (four MPP and four SPP with a specified amplitude and velocity). The amplitudes of vastus lateralis (VL), vastus medialis (VM), hamstrings lateralis (HL), hamstrings medialis (HM) EMG activity, medio-lateral and anterior-posterior centre of mass (COM) displacements, the peak knee flexion and abduction angles were compared between conditions using an one-way ANOVA. Number of stepping responses were monitored during all conditions.ResultsSignificantly greater muscle activity levels were found in response to the more challenging MPP and SPP compared to the less challenging conditions (p < 0.05). No differences in neuromuscular activity were found between the MPP conditions and their equivalents in the SPP. Eighteen stepping responses were monitored in the SPP versus nine in the MPP indicating that the overall neuromuscular control was even more challenged during the SPP which was supported by greater COM displacements in the SPP.ConclusionThe more intense MPP and SPP evoked different neuromuscular responses resulting in greater muscle activity levels compared to small perturbations. Based on the results of COM displacements and based on the amount of stepping responses, dynamic neuromuscular control of the knee joint appeared less challenged during the MPP. Therefore, future work should investigate extensively if other neuromuscular differences (i.e. co-activation patterns and kinetics) exist between MPP and SPP. In addition, future work should examine the influence on the neuromuscular control of the magnitude of the perturbations and the magnitude of stepping height and stepping distance.

Lower limb ice application alters ground reaction force during gait initiation.

BACKGROUND: Cryotherapy is a widely used technique in physical therapy clinics and sports. However, the effects of cryotherapy on dynamic neuromuscular control are incompletely explained. OBJECTIVES: To evaluate the effects of cryotherapy applied to the calf, ankle and sole of the foot in healthy young adults on ground reaction forces during gait initiation. METHOD: This study evaluated the gait initiation forces, maximum propulsion, braking forces and impulses of 21 women volunteers through a force platform, which provided maximum and minimum ground reaction force values. To assess the effects of cooling, the task - gait initiation - was performed before ice application, immediately after and 30 minutes after removal of the ice pack. Ice was randomly applied on separate days to the calf, ankle and sole of the foot of the participants. RESULTS: It was demonstrated that ice application for 30 minutes to the sole of the foot and calf resulted in significant changes in the vertical force variables, which returned to their pre-application values 30 minutes after the removal of the ice pack. Ice application to the ankle only reduced propulsion impulse. CONCLUSIONS: These results suggest that although caution is necessary when performing activities that require good gait control, the application of ice to the ankle, sole of the foot or calf in 30-minute intervals may be safe even preceding such activities.

Inter-joint coordination of overground versus treadmill walking in young adults

This study compares the pattern and variability of inter-joint coordination between treadmill and overground walking. Gait analyses of five young adults were performed during preferred speed overground walking (GPS), preferred speed treadmill walking (TPS), and treadmill walking with overground preferred speed (TGS). Continuous relative phase (CRP), derived from the phase portraits of two adjacent joints, was used to examine the inter-joint coordination. Cross-correlation measures and root-mean-square (RMS) differences were used to compare CRP patterns of the GPS condition to those of TPS and TGS conditions respectively. The deviation phase (DP) was used to evaluate the variability of inter-joint coordination during the stance and swing phases over a gait cycle for each condition. The walking speed of TPS was significantly slower than those of GPS and TGS. For the hip–knee CRP pattern, the RMS differences between GPS and TPS were significantly greater than the RMS differences between GPS and TGS. No significant differences between conditions were detected for the cross-correlation measures of hip–knee and knee–ankle CRP patterns. During the stance phase, the hip–knee DP values of TGS were significantly smaller than that of GPS and the knee–ankle DP values of TGS were also significantly smaller than that of GPS and TPS. No significant differences were detected for all three conditions in the swing phase. The findings suggest that the treadmill imposes a systemic regulation on dynamic neuromuscular control during walking, which may need to be considered while interpreting treadmill-based analysis of training to overground walking.

Knee Cooling Alters Dynamic Neuromuscular Control and Decreases Joint Laxity

PURPOSE: To determine whether focal knee cooling attenuates dynamic postural stability or decreases knee laxity and hamstring flexibility as compared to a room temperature trial. METHODS: Single-group, pretest-posttest control session design. Setting: University exercise physiology laboratory. Participants: Fourteen healthy college students (24 ± 3 years old). Intervention: Twenty-minute 5°C cooling pad application to the knee vs. room temperature (no cooling). Main Outcome Measures: Postural stability, anterior knee laxity and hamstring flexibility were measured before, immediately after and 20 minutes after either no cooling or a cooling pad application for 20 minutes. Skin temperature (lateral knee joint line) and subcutaneous temperature (medial knee joint line) were recorded every 5 minutes for the entire 20-minute treatment and for the 20-minute period following application. RESULTS: Mean medial-lateral deflection (frontal plane position) measurement of postural stability increased immediately following cooling from.60 ±.59 to.93 ±.80. Anterior knee laxity decreased immediately following cooling from 8.40 ±.79 to 7.48 ±.78 mm. These differences were no longer evident following 20 minutes of rewarming at room temperature. Hamstring flexibility did not change with cooling. Skin temperatures decreased with cooling from 30.34 ±.89 to 18.26 ± 2.28°C and remained lower (24.99 ±.93°C) following 20 minutes of rewarming. Subcutaneous temperatures decreased with cooling from 28.40 ± 1.41 to 16.13 ± 2.59°C and remained lower (21.94 ± 1.38°C) following 20 minutes of rewarming. CONCLUSIONS: Application of a cooling pad to the knee attenuates or alters dynamic neuromuscular control in the frontal plane and decreases knee compliance immediately following the application. Cold treatment is commonly used following acute injury in sport and exercise. Alterations in the dynamic joint stability and biomechanic properties of the knee with cooling may increase the risk of injury if exercise or sport is resumed immediately following cold treatment.